Relay construction

ABSTRACT

A relay construction having an energizable and deenergizable electrical winding operable to effect movements of an armature to and from a switch-closing position and wherein a non-conductive, elastomeric pad is interposed between the switch contacts, the elastomeric pad containing discrete, normally separated, electrically conductive particles dispersed therein in such quantity as to render the pad electrically conductive in response to compression thereof. The pad is mounted in such position as to be compressed in response to movement of the armature toward its switch-closing position. The elastomeric pad may be impregnated with or immersed in a lubricant and may form part of an electrically non-conductive, oil impervious seal or gasket for effect an environmental seal for the operating parts of the relay.

United States Patent 1191 Du Rocher Jan. 8, 1974 RELAY CONSTRUCTIONPrimary Examiner-l-larold Broome [75] Inventor: Gideon A. Du Rocher, Mt.Clemens, Atmmey john Lemma et Mich. 173] Assignee: Essex InternationalInc., Port [57] ABSTRACT Wayne, Ind. A relay construction having anenergizable and deena ergizable electrical winding operable to effectmove- 1972 ments of an armature to and from a switch-closing p0 [21]Appl. No.: 232,145 sition and wherein a non-conductive, elastomeric padis interposed between the switch contacts, the elastomeric padcontaining discrete, normally separated, g fi lg electrically conductiveparticles dispersed therein in [58] Fieid 5 133. such quantity as torender the pad electrically conductive in response to compressionthereof. The pad is 338/100 200/166 166 G mounted in such position as tobe compressed in response to movement of the armature toward its [56]References i switch-closing position. The elastomeric pad may be UNITEDSTATES PATENTS impregnated with or immersed in a lubricant and may2,951,817 9/1960 Myers 338/100 form part of an electricallynon-conductive, oil imper- 3,509.296 4/1970 Harshman at 333/114 viousseal or gasket for effect an environmental seal $235 32 71 5 for theoperating parts of the relay.

18 Claims, 10 Drawing Figures ww'av 4 i I' l/52711 vr 4 PATENTEU 8W43,784,941

SHEET 2 [IF 2 RELAY CONSTRUCTION A relay of the kind to which theinvention relates includes an electrical winding which may be connectedto and disconnected from a source of electrical energy so as to energizeand deenergize the winding and thereby act on an armature to effectmovements of the latter between two positions. In one position of thearmature electrical switch contacts are closed, thereby enabling acurrent path to be established between a source of electrical potentialand an instrumentality to be operated. In the other position of thearmature the switch contacts are open, thereby breaking the current pathto the instrumentality. In such a relay the distance I through which theswitch contacts are moved must be sufficient to assure snuffing orextinguishing of any are which occurs between the contacts as they moveapart.

The ability of an arc to survive is proportionate to the current valuesor, stated differently, when a relay controls a current of high valuethe switch contacts must be capable of substantial movement to assureextinguishing of the arc. The distance the switch contacts must move toassure arc extinguishing requires proportional movement of the armatureand, consequently, a proportional size gap in the magnetic flux path ofwhich the armature is a part. The greater the gap in the magnetic fluxpath, the larger and more expensive must be the electrical winding whicheffects movements of the armature. Moreover, the greater the distancethe armature must move to close or reduce the gap, the greater is itsvelocity and the greater is the noise of operation of the relay.

A relay constructed in accordance with the invention overcomes theaforementioned problemsvby interposing between the switch contacts ofthe relay a resilient, compressible pad which is non-conductive in itsnormal or uncompressed condition, but which contains a plurality ofdiscrete, electrically conductive particles in such quantity that asufficient number thereof move in engagement with one another inresponse to compression of the body and establish an electricallyconductive path through the body. The resilience of the pad is suchthat, when the compressive force applied to it is relieved, theparticles move out of engagement and render the pad non-conductive,thereby enabling the dielectric material of which the pad is constructedto effect snuffing of any are which otherwise would exist between theswitch contacts. As a result of the characteristics of the elastomericpad, the switch contacts need partake of relatively small movement, thearmature need partake of relatively amall movement, and

the size of the electrical winding necessary to effect such movement ofthe armature can be correspondingly small.

It has been proposed heretofore to immerse relays in oil to assist inare quenching and to reduce the operating noise, but not all suchconstruction have been wholly satisfactory. One of the difficultiesencountered with such known relays is that of chemical breakdown orcracking of the oil due to the presence of arcs. A relay constructedaccording to the invention, however, can be immersed in oil withoutexperiencing such difficulty because at least a portion of whateveracring occurs takes place within the elastomeric pad and, consequently,minimizes chemical reactions in the oil itself.

Another difficulty experienced with oil-immersed relays of conventionalconstruction is that of effecting a seal for the relay housing toprevent the inadvertent escape of the oil. A relay constructed accordingto one embodiment of the invention overcomes this problem by theprovision of an elastomeric, resilient seal or gasket havingself-contained, conductive parts by means of which current paths can beestablished between the interior and the exterior of the relay housingand which also includes a peripheral, compressible sealing bead whichmay be compressed between the separable com ponents of the relayhousing.

A relay constructed according to the invention possesses an outstandingand surprising capacity for accommodating not only high, steady current,but also extremely high transient or inrush currents over sustainedperiods of time and with remarkably low voltage losses. Thesecharacteristics are believed to be due to the presence of a large numberof low resistance, conductive particles in the elastomeric switch pad,thereby providing multiple current paths at the interfaces of the switchcontacts, coupled with the ability of the elastomer to conform toirregular surfaces at the interfaces and thereby avoid excessively highcurrent density at any current path.

An object of this invention is to provide a relay construction which iscapable of effecting switching of high value currents, but whichminimizes the distance the switch contacts and the armature must bemoved, thereby reducing the size and expense of electrical windingsassociated with the relay.

Another object of the invention is to provide a relay of the characterdescribed wherein the switching means functions also to cushion themovement of the arma ture and eliminate or greatly minimize the noiseasso ciated with armature movement.

A further object of the invention is to provide a relay constructionwhich is compatible for use with either oil-immersed relays or relaysexposed to air.

Another object of the invention is to provide a switching relay whichcan accommodate high, steady current values and exceedingly hightransient current values.

Other objects and advantages of the invention will be pointed outspecifically or will become apparent from the following description whenit is considered in conjunction with the appended claims and theaccompanying drawings, wherein:

FIG. I is a vertical sectional view through a relay constructed inaccordance with one embodiment ofthe invention and taken on the line l-Iof FIG. 3;

FIG. 2 is a view similar to FIG. I, but rotated through and taken on theline 22 of FIG. 3;

FIG. 3 is a top plan view;

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 1;

FIG. 5 is a sectional view taken on the line 5-5 of of FIG. 1;

FIG. 6 is a schematic wiring diagram illustrating the electricalcircuitry associated with the relay of FIG. 1;

FIG. 7 is a top plan view of a modified relay;

FIG. 8 is a sectional view taken on the line 8-8 of FIG. 7;

FIG. 9 is a sectional view taken on the line 9-9 of FIG. 8; and

FIG. 10 is an end elevational view.

A relay constructed in accordance with the embodiment of the inventiondisclosed in FIGS. 1-5 includes a generally cup-shaped, open end housingI having a cylindrical side wall 2 upstanding from a bottom wall 3 andhaving an outwardly turned rim 4 at its open end. At the center of thebottom wall 3 is an upstanding stop 5. Positioned within the housing 1is a nonmagnetic bobbin 6 on which is wound an annular winding 7 ofmagnet wire. The opposite ends 8 and 9 of the winding are locatedadjacent the open end of the housing.

The bobbin has a central core 10 within which is slidably accommodated amagnetic armature 11 having a reduced extension 12 at its upper end onwhich is mounted a phenolic grommet 13 having a peripheral flange 14.The free end of the extension 12 is peened over as at 15 to bear againstthe grommet 13.

Fitted onto the bobbin core 10 adjacent the open end of the housing 2 isan annular, magnetic member 16 the periphery of which engage the housingwall 2 to form a part of the magnetic flux path. Also fitted onto thebobbin core 10 is an annular, dielectric member 17 of such diameter asto seat upon the rim 4 at the open end of the housing. The member 17carries on its outer surface an electrically conductive disc 18 adjacentthe periphery of the member 17 and a centrally located, annular,conductive member 19 through which the bobbin core 10 extends. Extendingradially from the member 19, and diametrically opposite the member 18,is an electrically conductive member 20. Each of the members 18 and 20preferably has an opening 21 therein through which the ends 8 and 9,respectively, of the winding 7 may pass so as to overlie the member 18and 20, as is best shown in FIG. 1. The leads 8 and 9, however, could besoldered or otherwise fixed to the conductors 18 and 20, if desired.

Overlying and supported on the member 17 is an electrically conductiveleaf spring 22 having an opening 23 between its ends for theaccommodation of the grommet 13. The spring 22 extends diametrally ofthe member 17 and normal to the diametral arrangement of the conductors18 and 20 so as to avoid engagement therewith. The central portion 24 ofthe spring 22 is bowed upwardly and bears against the under side of ametallic washer 25 which protects the grommet flange 14 against wear.The spring 22 biases the armature 11 in a direction toward the open endof the housing 1 so that a gap 26 exists between the armature 11 and thestop 5 when the winding 7 is deenergized.

A combined seal and contact carrier 27 overlies the contacts 18 and 20and comprises a resilient, generally disc-like web 28 molded ofelectrically insulating material such as silicone rubber. At theperiphery of the web 28 is an annular flange or bead 29 which fitswithin the rim 4 and bears against the latter and against the peripheryof the member 17. The bead 29 extends axially beyond the member 17 for apurpose presently to be explained. The central portion of the web 28 isstepped to form a boot 30 which overlies the armature 11 and itsassociated parts. The web 28 preferably includes a radially projectingtongue 31 that may be accommodated in a slot 32 formed in the rim 4 ofthe housing to facilitate proper orientation of the carrier 27 relativeto the other parts of the relay.

The web 28 of the carrier 27 is provided with three openings 33, 34, and35 each of which receives a contact pad 36. Each pad comprises a molded,resilient, compressible, dielectric substance, such as silicone rubberof the same kind as that forming the web 28, and throughout which aplurality of discrete, electrically conductive particles are dispersed.The size and quantity of the particles are such that they may establishelectrically conductive paths through the pads 36. The pads preferablyare thicker than the web 28 so as to project beyond both sides of thelatter and are either bonded after molding to the edges of the openingsor are adhered thereto by being molded in situ. The structural andelectrical characteristics of the pads 36 and the manner in which theymay be formed are disclosed in U.S. Pat. No. 3,648,002 to whichreference may be had for a more detailed description.

The pads 36 are so arranged that, when the contact cartier 27 isassembled with the housing 1, one pad 36 overlies the conductor 18 andthe winding lead 8, a second pad overlies the conductor 20 and thewinding lead 9, and the third pad overlies one end of the spring 22.

A cover 37 of non-conductive material is provided for the housing 1 andincludes a central stepped portion 38 from which extends a peripheralflange 39 that fits snugly within the rim 4 of the housing. Carried bythe cover are three conductive blades 40, 41, and 42 having legs 43, 44,and 45, respectively, bent to underlie the flange 39. The legs 43, 44,and 45 overlie the pads 36 in the respective openings 33, 34 and 35. Thecover 37 is maintained assembled with the housing 1 by a plurality ofclamp fingers 46 carried by the body wall 2 and bent over the coverflange 39.

Inasmuch as the bead 29 of the carrier 27 projects axially beyond themember 17, it may be engaged with substantial force by the cover flange39 so as to cause the bead to be compressed and effect a tight sealbetween the housing and the cover and between the carrier and the member17. The contacts 18, 19, and 20 thus are sealed within the housing.Moreover, the legs of the conductive blades 4042 bear forcibly againstthe pads 36 so as to compress the latter and assure engagement ofsufficient conductive particles in each pad to render the latterelectrically conductive.

An annular switching member 47 encircles the bobbin core 10 and isinterposed between the annular contact 19 and the spring 22. Theswitching member comprises a pad of resilient, compressible, dielectricmaterial such as silicone rubber throughout which is dispersed aplurality of electrically conductive particles. The particles preferablyare copper spheres coated with a low resistance, noble metal such assilver and are of such size and are present in such quantity that, inits uncompressed condition, the pad 47 is nonconductive. When the pad issubjected to compression, however, enough conductive particles move intoengagement with one another to establish a plurality of electricallyconductive paths through the body between the contact 19 and the spring22.

FIG. 6 is a schematic wiring diagram ofa typical relay circuit anddepicts the blade 42 connected to the positive terminal of a battery orother source of electrical potential and the blade 40 connected toground potential so that, upon closing of a switch 48, the winding 7energized via the blade 42, a pad 36, the lead 8, the lead 9, a secondpad 36, and the blade 40. The elements 42, 36, 36 and 40 constituteterminal means for connecting the winding to the energy source. Uponenergization of the winding 7, the armature 11 is displaced toward thethe stop 5, compressing the switching member 47 between the spring 22and the conductor 19 and rendering the switching member conductive,thereby establishing an electrically conductive path between the spring22, the conductor 20, the third pad 36, and the blade 41 which may beconnected to an instrumentality such as the winding 49 of a vehiclestarter motor, or the like. The elements 19, 20, 22, 36 and 41constitute an output or load circuit.

The carrier 27 forms such an effective seal between the housing and thecover that all of the working parts of the relay are completely sealedagainst the introduction of foreign matter to the interior of thehousing. The seal also is so effective that the housing may be filledwith oil to obtain the beneficial cooling and noise suppression affordedthereby. It is preferred that sufficient oil be introduced to thehousing 1 to occupy the interior of the stepped portion 30 of thecarrier 27 and surround the member 47 so as to form an interface betweenthe'switching member 47 and the members 19 and 22. The oil should be onewhich is compatible with silicone rubber, and there are manycommerically available oils suitable for this purpose. The oil isbelieved to aid in the quenching of arcs which may occur between themembers 19 and 22 and the switching member 47 and also provides avehicle by means of which the residue of such arcing may be removed fromthe vicinity of the pad 47, thereby prolonging the life of the latter.

Itis not essential that oils be contained within the stepped portion 30of the contact carrier 27. The benefical results of the presence of alubricant at the switching member 47 can be achieved by either coatingor impregnating the body with a machine oil compatible with siliconerubber, and like that used on the ways of a machine tool, or a pastylubricant such as that manufactured by Fiske Brothers Refining Company,Toledo, Ohio, marketed under the trademark LUBRI PLATE, and designatedDS grade No. 0. The paste lubricant should be capable of withstanding300 F. without vaporization and be compatible with the base siliconeresin. Satisfactory results have been obtained using the LUBRIPLATElubricant referred to above in amounts equal to 0.3 O.6 grams per gramof base silicone resin, excluding the catalyst.

The embodiment of the invention disclosed in FIGS. 7-10 comprises aclapper type relay having an insulating base 50 on which a mountingbracket 51 is secured by screws 52 or the like. Secured to the bracket51 by one or more screws 53 is one leg 54 of a generally U shaped,magnetic yoke 55 having a second leg 56 which extends through the core57 of a bobbin 58 formed of insulating material and on which is wound anelectrical winding 59. The leg 56 is joined to a third leg 60 which,instead of paralleling the leg 54, extends at an angle thereto for apurpose presently to be explained.

Between the base 50 and the free ends of the yoke legs 54 and 60 is amagnetic armature 61 which is mounted on a fulcrum 62 supported on thebase 50 beneath the leg 54. One end of the armature 61 terminates justshort of the leg 60 to form an air gap 63 therebetween and the other endof the armature 61 extends beyond the bracket 51 to overlie a cavity 64in the base. Fixed to the lower surface of the armature 61 by means ofascrew 65 is a block of insulating material 66. The screw 65 also formsan anchor for one end of a tension spring 67, the opposite end of whichis secured to an anchor screw 68 carried by the yoke leg 54.

A blade terminal 69 extends through the base 50 into the cavity 64 andhas a leg 70 which seats on the base of the cavity. Atop the leg 70 is aswitching member 71, similar to the member 47, comprising a pad ofelastomeric, electrically non-conductive material such as sili- 6 conerubber throughout which is dispersed a quantity of electricallyconductive, discrete, metallic particles. The switching member 71 issandwiched between the leg and an electrically conductive foot member 72that is carried by the block 66 and is of such size as to beaccommodated in the cavity 64.

One end 73 of the winding 59 extends from the latter to the cavity 64formed in the base 50 and is sand wiched between the pad 71 and the leg70 of the terminal 69. In engagement with the conductive foot 72 is oneend of a conductor 74, the opposite end of which extends to a cavity 75in the base and is sandwiched between a pad 76, like the pad 36, and aleg 77 ofa blade terminal 78 that is secured to the base and whichmaintains the pad 76 under sufficient compressive force as to maintain asufficient number of particles therein in engagement to render the padconductive. The other end 79 of the winding 59 extends to a cavity 80 inthe base and is sandwiched between a pad 81, like the pad 76, and a leg82 of a blade terminal 83 which extends through the base. The terminalleg 82 maintains the pad 81 under sufficient compression to render itconductive and thereby establish electrical continuity be tween theconductor 79 and the terminal 83.

The terminal 78 is adapted for connection to a source of electricalpotential and the terminal 83 is adapted for connection to the oppositeterminal of the source or to ground potential. The terminal 69 isadapted for connection to an instrumentality to be operated. Theterminals 78 and 83, together with their associated parts, constitutemeans for energizing the winding 59 through a switch (not shown) similarto the switch 48, and the terminals 78 and 69, together with theirassociated parts, constitute a load circuit of which the switchingmember 71 is a part.

When the winding 59 is deenerized, the armature 61 assumes the positionshown in full lines in FIG. 8 due to the effect of the spring 67. Whenthe winding is energized, however, the armature is caused to rockclockwise about the fulcrum 62, thereby stretching the spring 67 amdcompressing the pad 71 so as to render the latter electricallyconductive and establish electrical continuity between the load circuitterminals 78 and 69.

The length of the armature from its free end to the fulcrum 62 isseveral times the length of the armature from the fulcrum to theconnection thereto of the spring 67, thereby providing a substantialmultiplica tion of the force applicable to the pad 71 in response toclockwise rocking of the armature. This force is sufficient to assurecompression of the pad 71 an amount sufficient to render it electricallyconductive and establish an electrical continuity through the loadcircuit.

The angular relation of the leg 60 is such that, during oscillation ofthe armature 61 in response to energization and deenergization of thewinding 59, the gap 63 is maintained substantially constant.

a The switching member 71 may be impregnated or coated with a lubricantsuch as those referred to above. Although the member 71 is not immersedin oil, the lubricant nevertheless assists in the quenching of arcs andserves to hold the by-products of arcing in suspension to prolong thelife of the switching member.

in each of the disclosed embodiments energization of the winding effectsmovements of the armature associated therewith to effect compression andclosing of the associated switch member. Since the armature acts on aswitch member which is composed in part of a re silient, rubberymaterial, the actuation of the armature virtually is noiseless.

The extent to which either of the switching pads must be compressed tochange it from its non-conductive to its conductive condition dependsupon several factors, such as its thickness, its durometer hardness, thequantity of particles contained therein, and the size of the particles.In general, the extent to which a pad must be compressed to render itconductive is inversely proportional to its thickness, the concentrationof particles, and the durometer hardness of the pad, and is directlyproportional to the size of the particles. Nevertheless, the conversionof a pad from non-conductivity to conductivity, and vice-versa, occurssubstantially instantaneously. Thus, only a small amount of compressionof a switching pad is necessary to render it conductive and acorresponding small amount of expansion of the pad is necessary torender it non-conductive. Consequently, only a corresponding smallamount of movement of an armature is necessary to effect propercompression of a pad to render it conductive and a correspondingly smallamount of movement of the armature in the reverse direction is necessaryto render the pad nonconductive. As soon as the pad is renderednonconductive, however, no arc can exist inasmuch as the pad thenbecomes an insulator. Thus, the movement of an armature in a relayaccording to the invention can be much less than that of conventionalrelays without risking damage due to arcing. As a consequence, considerable economies can be achieved with relays of the kind hereindisclosed.

The specific force which must be applied to a particular switchingmember 47 or 71 to render it electrically conductive can be determinedempirically. The force that can be applied on a switching member by arelay armature is directly related to the physical characteristics ofthe armature and the relay winding and to the electrical characteristicsof the relay energizing circuit.

The physical and electrical properties of the particles dispersedthroughout the switching pads will vary according to several factorssuch as the steady and transient current value which must beaccommodated by the particles, the force available for compression ofthe pads, and the resistance of the particles. In general, the particlesshould constitute between about 78 percent and 93 percent of the weightof a switching pad and may be spherical having a diameter of betweenabout 0.005 and 0.100 inch. The particles preferably comprise copperspheres having an exterior coating of silver. Such particles are lessexpensive then wholly silver particles, but have substantially the sameelectrical resistance. Another advantage of silver-coated particles isthat the oxidation to which silver is subjected is electricallyconductive, rather than non-conductive.

Relays constructed according to the invention have been subjected toextensive testing. The test results indicate uniformly that a relaysincorporating a switching member such as those herein disclosed operatemuch more quietly than conventional relays and are capable ofaccommodating inrush current values much higher than heretofore thoughtpossible, and without sacrificing the longevity of the relays. Thischaracteristic of relays constructed according to the invention isbelieved to be due partly to the ability of the resilient pad to conformto surface irregularities which inevitably exist between confrontingcontacts and thereby provide a relatively large conductive area betweensuch contacts. and partly to the presence of such a large number ofconductive particles in the pad to provide a very large number ofconductive paths through the pad and thereby avoid the high currentdensity associated with one or only a few current paths.

Although spring devices have been disclosed for the purpose of assuringexpansion of the switching members 47 and 71 and return movement of therespective armatures, the springs could be eliminated in many instancesdepending on the resilient properties of the switching members. That is,the resilience of a particular switching member could be such that itmay expand sufficiently to become non-conductive and return its armaturein response to deenergization of the associated winding. If the spring22 is omitted from the embodiment shown in FIGS. 1-5, some conductiveelement will have to be substituted therefor so as to bridge thedistance between the pad 47 and the associated pad 36. Such a conductormay be a conventional, conductive wire.

The disclosed embodiments are representative of presently preferredforms of the invention, but are intended to be illustrative rather thandefinitive thereof. The invention is defined in the claims.

What is claimed is:

1. A relay construction comprising an electrically energizable anddeenergizable winding; means for connecting and disconnecting saidwinding to a source of electrical potential; an armature responsive tosuccessive energization and deenergization of said winding to move inopposite directions; load circuit means including first and secondspaced apart conductors; normally non-conductive switching meansengaging said first and second conductors operable to connect anddisconnect said load circuit means to and from a source of electricalpotential, said switching means comprising an elastomeric body ofdielectric material having a quantity of discrete, electricallyconductive particles dispersed therein, the quantity and dispersion ofsaid particles being such that a sufficient number thereof move intoengagement with one another in response to compression of said body toestablish through said body and between said first and second conductorsan electrically conductive path having a resistance corresponding substantially to the resistance of said particles; and means mounting saidswitching means for compression of said body in response to movement ofsaid armature in one direction.

2. The construction set forth in claim 1 wherein said armature isreciprocable.

3. The construction set forth in claim 2 wherein one end of saidarmature extends beyond a fixed member on which said body is supported,said one end of said armature carrying a part for engaging said body andcompressing the latter between said part and said memher.

4. The construction set forth in claim 3 wherein said load circuit meansincludes a conductor carried by said fixed member and in engagement withsaid body.

5. The construction set forth in claim 4 wherein one of the conductorsof said load circuit means is connected to said means for connecting anddisconnecting said winding to its source of electrical potential.

6. The construction set forth in claim 5 wherein said body is sandwichedbetween said first and second conductors.

7. The construction set forth in claim 6 wherein said one of saidconductions is resilient and biases said armature to move in theopposite direction to relieve the compression of said body.

8. The construction set forth in claim 1 wherein the elastomericdielectric material of said body biases said armature to move in theopposite direction to relieve the compression of said body.

9. The construction set forth in claim 1 wherein said armature isoscillatable.

10. The construction set forth in claim 9 wherein said armature overliesa fixed member on which said body is supported.

11. The construction set forth in claim 9 wherein said armature liesadjacent but spaced from magnetic means to form an air gap, saidmagnetic means being configured to permit oscillation of said armatureand maintain said air gap substantially constant.

12. The construction set forth in claim 1 including spring means actingon said armature and biasing the latter to move in a direction away fromsaid body.

13. The construction set forth in claim 1 wherein said body is coatedwith a quantity of lubricant in addition to said conductive particles.

14. The construction set forth in claim 1 including a housing withinwhich said winding is enclosed, said housing containing a lubricant.

15. The construction set forth in claim 1 including a housing withinwhich said winding is enclosed, a cover for said housing, and a seal ofdielectric material interposed between said cover and said housing, saidseal having a plurality of openings therein each of which is filled witha pad of elastomeric, dielectric material containing a plurality ofdiscrete, conductive particles therein in such quantity as to rendersaid pad electrically conductive, said means for connecting anddisconnecting said winding to and from its said source including saidpads.

16. The construction set forth in clairn 33 including means subjectingeach of said pads to compressive force.

17. A relay construction having an energizable and deenergizablewinding; an armature responsive to successive energization anddeenergization of said winding to move in opposite directions; loadcircuit means adapted for energization and deenergization in response tomovements of said armature, said load circuit means including first andsecond spaced apart conductors; switching means connected in circuitwith said load circuit means; means mounting said switching means inengagement with said first and second conductors and in the path ofmovement in one direction of said armature for engagement thereby, saidswitching means comprising a body formed of elastomeric, dielectricmaterial having a plurality of discrete, elec trically conductiveparticles dispersed therein, the quantity of particles in said bodybeing such that the latter is non-conductive when in a non-compressedcondition but is conductive when subjected to compressive force ofpredetermined magnitude, said winding and said armature being so relatedto one another that a change in the energized state of said windingeffects movement of said armature in said one direction and compressionof said body under a force of such magnitude as to render itelectrically conductive; and a lubricant other than said conductiveparticles coating said body.

18. The construction set forth in claim 17 wherein said body is immersedin said lubricant.

* l i =l

1. A relay construction comprising an electrically energizable anddeenergizable winding; means for connecting and disconnecting saidwinding to a source of electrical potential; an armature responsive tosuccessive energization and deenergization of said winding to move inopposite directions; load circuit means including first and secondspaced apart conductors; normally nonconductive switching means engagingsaid first and second conductors operable to connect and disconnect saidload circuit means to and from a source of electrical potential, saidswitching means comprising an elastomeric body of dielectric materialhaving a quantity of discrete, electrically conductive particlesdispersed therein, the quantity and dispersion of said particles beingsuch that a sufficient number thereof move into engagement with oneanother in response To compression of said body to establish throughsaid body and between said first and second conductors an electricallyconductive path having a resistance corresponding substantially to theresistance of said particles; and means mounting said switching meansfor compression of said body in response to movement of said armature inone direction.
 2. The construction set forth in claim 1 wherein saidarmature is reciprocable.
 3. The construction set forth in claim 2wherein one end of said armature extends beyond a fixed member on whichsaid body is supported, said one end of said armature carrying a partfor engaging said body and compressing the latter between said part andsaid member.
 4. The construction set forth in claim 3 wherein said loadcircuit means includes a conductor carried by said fixed member and inengagement with said body.
 5. The construction set forth in claim 4wherein one of the conductors of said load circuit means is connected tosaid means for connecting and disconnecting said winding to its sourceof electrical potential.
 6. The construction set forth in claim 5wherein said body is sandwiched between said first and secondconductors.
 7. The construction set forth in claim 6 wherein said one ofsaid conductions is resilient and biases said armature to move in theopposite direction to relieve the compression of said body.
 8. Theconstruction set forth in claim 1 wherein the elastomeric dielectricmaterial of said body biases said armature to move in the oppositedirection to relieve the compression of said body.
 9. The constructionset forth in claim 1 wherein said armature is oscillatable.
 10. Theconstruction set forth in claim 9 wherein said armature overlies a fixedmember on which said body is supported.
 11. The construction set forthin claim 9 wherein said armature lies adjacent but spaced from magneticmeans to form an air gap, said magnetic means being configured to permitoscillation of said armature and maintain said air gap substantiallyconstant.
 12. The construction set forth in claim 1 including springmeans acting on said armature and biasing the latter to move in adirection away from said body.
 13. The construction set forth in claim 1wherein said body is coated with a quantity of lubricant in addition tosaid conductive particles.
 14. The construction set forth in claim 1including a housing within which said winding is enclosed, said housingcontaining a lubricant.
 15. The construction set forth in claim 1including a housing within which said winding is enclosed, a cover forsaid housing, and a seal of dielectric material interposed between saidcover and said housing, said seal having a plurality of openings thereineach of which is filled with a pad of elastomeric, dielectric materialcontaining a plurality of discrete, conductive particles therein in suchquantity as to render said pad electrically conductive, said means forconnecting and disconnecting said winding to and from its said sourceincluding said pads.
 16. The construction set forth in claim 33including means subjecting each of said pads to compressive force.
 17. Arelay construction having an energizable and deenergizable winding; anarmature responsive to successive energization and deenergization ofsaid winding to move in opposite directions; load circuit means adaptedfor energization and deenergization in response to movements of saidarmature, said load circuit means including first and second spacedapart conductors; switching means connected in circuit with said loadcircuit means; means mounting said switching means in engagement withsaid first and second conductors and in the path of movement in onedirection of said armature for engagement thereby, said switching meanscomprising a body formed of elastomeric, dielectric material having aplurality of discrete, electrically conductive particles dispersedtherein, the quantity of particles in said body being such that thelatter is non-condUctive when in a non-compressed condition but isconductive when subjected to compressive force of predeterminedmagnitude, said winding and said armature being so related to oneanother that a change in the energized state of said winding effectsmovement of said armature in said one direction and compression of saidbody under a force of such magnitude as to render it electricallyconductive; and a lubricant other than said conductive particles coatingsaid body.
 18. The construction set forth in claim 17 wherein said bodyis immersed in said lubricant.